mmc: sdhci-esdhc: break out early if clock is 0

Since commit 30832ab56 ("mmc: sdhci: Always pass clock request value
zero to set_clock host op") was merged, esdhc_set_clock starts hitting
"if (clock == 0)" where ESDHC_SYSTEM_CONTROL has been operated.  This
causes SDHCI card-detection function being broken.  Fix the regression
by moving "if (clock == 0)" above ESDHC_SYSTEM_CONTROL operation.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/host/sdhci-esdhc.h

@@ -48,14 +48,14 @@ static inline void esdhc_set_clock(struct sdhci_host *host, unsigned int clock)
 	int div = 1;
 	u32 temp;
 
+	if (clock == 0)
+		goto out;
+
 	temp = sdhci_readl(host, ESDHC_SYSTEM_CONTROL);
 	temp &= ~(ESDHC_CLOCK_IPGEN | ESDHC_CLOCK_HCKEN | ESDHC_CLOCK_PEREN
 		| ESDHC_CLOCK_MASK);
 	sdhci_writel(host, temp, ESDHC_SYSTEM_CONTROL);
 
-	if (clock == 0)
-		goto out;
-
 	while (host->max_clk / pre_div / 16 > clock && pre_div < 256)
 		pre_div *= 2;